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    <meta charset="UTF-8">
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    <title>Document</title>
</head>
<body>
    <script>
        
    console.time('测试开始')

    console.log('输出信息');

    console.warn('输出警告信息');

    console.error('输出错误信息');

    console.timeEnd('测试结束')
    var a =  100 	
    
    console.log('a的类型：'+ typeof a); 

    var b =  55.55
    
    console.log('b的类型：'+ typeof b);

    var c = true  

    console.log('c的类型：'+ typeof c);

    var d = false 	
    
    console.log('d的类型：'+ typeof d);

    var e = "Helloworld" 
    
    console.log('e的类型：'+ typeof e);

    var f = 'Helloworld'	

    console.log('f的类型：'+ typeof f);

    var student = {
    
    name:'张三',
    age:20,
    study( ){
    console.log('学习');
    },
    play(){
        console.log('玩');
    }
    
    }
    console.log('stydent的类型：'+ typeof student);

    var g = null 

    console.log('g的类型：'+ typeof g);

    g = 100 

    console.log('g的类型：'+ typeof g);

    var f = undefined 
    
    console.log('f的类型：'+ typeof f); 
    
    var h
    
    </script>
</body>
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